The invention relates to a fuel cut-off anti-theft device for a vehicle.
Many fuel cut-off anti-theft devices of the type comprising a fuel control valve which has an operating means for moving the valve between an open and a closed position and control means for operating the valve are known. In conventional arrangements the control means and/or the valve can be relatively easily tampered with to allow the thief to open the valve and allow flow of fuel.
One such device is described in French Patent Specification No. 2562012 (Wittver). Wittver describes a fuel cut-off anti-theft device comprising an electric solenoid valve, an electronic circuit, a relay center and a keypad. A DC signal from the keypad is outputted along a line to the relay center which, provided the carried signal is received, converts the DC signal into an AC signal which is outputted along another line to the electronic circuit where the signal from the relay center is converted back into a DC signal to operate the solenoid valve. The solenoid valve is mounted on the fuel line. The relay center however, is situated in the dashboard of the vehicle. In the Wittver system either of the lines from the keypad to the relay center or from the relay center to the control circuitry are readily accessible and can be successfully interfered with. Indeed, Wittver admits that a separate alarm would be required if the line from the keypad to the relay were tampered with.
U.S. Pat. No. 3,756,341 (Tonkowich) describes a keypad operated fuel cut-off anti-theft device, however, the unit may be easily tampered with as the control circuitry for the valve is readily accessible.
French Patent Specification No. 2550499 (Bayard) also describes a fuel cut-off anti-theft device however, there are no worthwhile tamper proofing measures proposed as the supply breaker is merely hidden in the dashboard.
There is therefore, a need for an improved cut-off anti-theft device for a vehicle.